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your innovative fiber optics provider
All FiberAll FiberAll FiberAll FiberPolarization ScramblerPolarization ScramblerPolarization ScramblerPolarization Scrambler
All FiberAll FiberAll FiberAll FiberAll FiberAll FiberAll FiberAll FiberPolarization ScramblerPolarization ScramblerPolarization ScramblerPolarization ScramblerPolarization ScramblerPolarization ScramblerPolarization ScramblerPolarization Scrambler
Your Solution for Polarization related ProblemsYour Solution for Polarization related Problems
YeonWan KohFiberPro Lab.
1your innovative fiber optics provider
ContentsContentsContentsContentsContentsContentsContentsContents
1. Introduction:
- Why PS?
2. Polarization scrambling:
- Principle and Methods- Features of FiberPro s PS
3. Applications
4. Conclusions
2your innovative fiber optics provider
Why PS?Why PS?Why PS?Why PS?Why PS?Why PS?Why PS?Why PS?Why PS?Why PS?Why PS?Why PS?
To solve the polarization-related problems in,
Communications
Measurements Sensors
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Limiting Factors in Amplified systems Cumulative Signal distortionsLimiting Factors in Amplified systems CumulatiLimiting Factors in Amplified systems Cumulative Signal distortionsve Signal distortions
J. Chesnoy, Alcatel, ECOC'97
Polarization effects
Polarization mode dispersion (PMD)
Polarization Dependent Loss (PDL)
•Temporal pulse broadening
•SNR fluctuations
Back-to-back
1000km span, Including CD, Nonlinear effect
Transmitted
Polarization Dependent Gain (PDG) •SNR average penalty
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Polarization effect in long haul systemsPolarization effect in long haul systemsPolarization effect in long haul systems
Simulation parametersPDG =0.14dB/EDFA
PDL =0.06dB/EDFA
PMD =0.13ps/sqrt(km)
Experimental parameters
1kHz scrambling speedSingle source(1558.6nm)
5Gbps, NRZ
with 181 EDFA, 4000km link
Improvement in the mean Q due to polariation scrambling vs. link length.at DOP < 10%
Mean penalty on the SNR in a 4000km linkMean penalty on the Q factor in a 4000km link
F. Bruyere, et. al., IEEE Photo. Technol. Lett., Vol. 6, No. 9, 1153 (1994)
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Polarization Problems in MeasurementPolarization Problems in MeasurementPolarization Problems in Measurement
• Example 1.
In long-haul DWDM system, Gain-Wavelength characteristics need to be tested precisely up to 0.005 - 0.01 dB
For equalization and etc.
! Input Light Power fluctuation by PDL
! Output Power fluctuation by PDG (~0.1dB)
! PDL in measurement equipment (0.03-0.1dB)
• Example 2.
Filters for telecommunications requires to set accurately less than 10GHz(0.08nm). PDL can give wrong value of center wavelength during interrogation.
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Polarization-Induced Phase Noise in FiberInterferometric SensorsPolarization-Induced Phase Noise in FiberPolarization-Induced Phase Noise in FiberInterferometricInterferometric Sensors Sensors
• Polarization Perturbations of Input Fiber! Visibility fluctuation
! Phase Noise
Input Fiber
Mach-Zehnder Interferometer
PD
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PPPPolarizationolarizationolarizationolarization SSSScramblingcramblingcramblingcrambling cancancancanPPPPPPPPolarizationolarizationolarizationolarizationolarizationolarizationolarizationolarization SSSSSSSScramblingcramblingcramblingcramblingcramblingcramblingcramblingcrambling cancancancancancancancan
solve the polarization-related problems in,
Communications - PDG in long EDFA chain
Measurement- Error caused by PDL of DUT & Measuring equipment
Sensors- Polarization induced phasenoise
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What is polarization scrambling?What is polarization scrambling?What is polarization scrambling?What is polarization scrambling?What is polarization scrambling?What is polarization scrambling?What is polarization scrambling?What is polarization scrambling?What is polarization scrambling?What is polarization scrambling?What is polarization scrambling?What is polarization scrambling?
A. Depolarizer: Removing correlation betwe
en polarization states
(Broadband Source)
e.g.: Lyot depolarizer
B. Polarization Scrambler: Modulate polarization state
(over Poincare sphere) (Monochromatic Source)
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Concept : Apply time varying phase delay between the two
orthogonal polarization modes.
How to make polarization scrambling?How to make polarization scrambling?How to make polarization scrambling?How to make polarization scrambling?How to make polarization scrambling?How to make polarization scrambling?How to make polarization scrambling?How to make polarization scrambling?How to make polarization scrambling?How to make polarization scrambling?How to make polarization scrambling?How to make polarization scrambling?
Time varyingPhase delay
modulation
modulation
PBSPBS
L
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Principle of Polarization ScramblingPrinciple of Polarization Scrambling
Monochromatic lightEx( t ) = a1 exp [ iϕ1(t) ]Ey( t ) = a2 exp [ iϕ2(t) ] δ = ϕ 1 - ϕ 2
General Stokes ParametersS0 = < a1
2 > + < a22
>S1 = < a1
2 > - < a22 >
S2 = 2 < a1 a2 cosδ >S3 = 2 < a1 a2 sinδ >
Effective Degree of Polarization
Peff. = Ipol. / Itot. = sqrt( S 12 + S2
2 + S32 ) / S 0 (0 < Peff < 1)
Effectively Depolarized Light ( Perfectly Scrambled Light )
Peff. = 0
{
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Electro-Optic Polarization ScramblersElectro-Optic Polarization Scramblers
• Fast Speed.
• Relatively small
• Phase chirp
• High PMD: ~ 17 ps
• Complex driving circuit
• High loss: > 5 dB
• Input Pol. Dependent
LiNbO3
Variable LinearPhase Retarder at 0o
P45o LinearInputSOP
x y
∆ϕ ( t )=Γy(2π/λ0) n0
3r12 L (V(t)/G) ∝ 1/1/1/1/λλλλ2222
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Mechanical/PM fiber Polarization scramblersMechanical/PM fiber Polarization scramblers
• Pseudo Random Pol. generation• Slow speed: ~100 rev./sec MAX• Not for DOP zero applications• High PMD (PM fiber type)
PM fiber
Trace for 2 second
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Polarization scrambling at PSPolarization scrambling at PSPolarization scrambling at PSPolarization scrambling at PSPolarization scrambling at PSPolarization scrambling at PSPolarization scrambling at PSPolarization scrambling at PS
Input polarization independentPolarization scrambling
For orthogonal polarization
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PoincarePoincare Sphere representation of Output SOP Sphere representation of Output SOP
Trace for 200 µsec
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Polarization Scrambler OutputPolarization Scrambler Output
INPUT OUTPUTPOWER
DISABLE
IO
F I B E R P R OF I B E R P R OF I B E R P R OF I B E R P R OALL FIBER OPTIC POLARIZATION SCRAMBLER PS-155-A-B
InputPolarizationState
PolarizationController
Polarizer
OutputPolarizationState
Input Polarization Independent
PolarizationController Receiver
PolarizedSource
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Output DOP Output DOP vsvs. Measurement Bandwidth. Measurement Bandwidth
• PS makes Zero DOP on time average.
• Measurement bandwidth is important parameter when using PS.
1 100
10
20
30
40
50
30kHz 170kHz 330kHz
DO
P(%
)
Cutoff Frequency(kHz)
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DOPDOP vs vs. Wavelength (center: 1549. Wavelength (center: 1549 nm nm))
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F I B E R P R O s All Fiber Optic Polarization ScramblerF I B E R P R O F I B E R P R O ss All Fiber Optic Polarization ScramblerAll Fiber Optic Polarization Scrambler
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PS for Rack mount(custom made)PS for Rack mount(custom made)
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Why Why Why Why Why Why Why Why FiberProFiberProFiberProFiberProFiberProFiberProFiberProFiberPro ssssssss PS? PS? PS? PS? PS? PS? PS? PS?
•• All Single Mode Fiber configurationAll Single Mode Fiber configuration
•• Low Loss < 1.5dB (with connectors)Low Loss < 1.5dB (with connectors)
•• Super Low PMD < 0.2Super Low PMD < 0.2 psec psec
•• High SpeedHigh Speed
•• Wide operating Wavelength Range: > 60nmWide operating Wavelength Range: > 60nm
•• Plug & PlayPlug & Play
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Typical applications of PSTypical applications of PSTypical applications of PS
•• Removing error frRemoving error from equipmentom equipment s Ps PDLDL
•• PDL independent mPDL independent measurement. Filter, Eeasurement. Filter, EDFA, and etc.DFA, and etc.
•• Improving SNR fromImproving SNR fromPDG, Pump PDG, Pump PolPol. . DepDep..in long-haul systemsin long-haul systems
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Set-up ~9000 km transmission
BER Improvement in Long-haul Transmission:Single channelBER Improvement in Long-haul Transmission:BER Improvement in Long-haul Transmission:Single channelSingle channel
F. Heismann, et. al., PTL, Vol. 6, No. 9, 1156 (1994)
BER after transmission
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SNR Improvement in Long-haul Transmission:SNR Improvement in Long-haul Transmission:Multi channelMulti channel
H. Taga, et.al., WE6-1, OFC 99 Technical Digest (1999)
Reduce accumulated ASE noise SNR improvement
After 9000km transmission
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Accumulated PDG/PDL in long EDFA chainAccumulated PDG/PDL in long EDFA chainAccumulated PDG/PDL in long EDFA chain
LD: Laser Diode
VA: Variable Attenuator
AOM: Acousto-Optic Modulator
PC: Polarization Controller
GFF: Gain Flattening Filter H.S. Cheong, et. al., Elect. Lett., Vol.34, 2045 (1998)
1535 1540 1545 1550 1555 1560 1565-50
-40
-30
-20
-10
0
200 EDFA PS OFF 200 EDFA PS ON
rela
tive p
ow
er
(dB
m)
wavelength (nm)
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IL Interrogation of DUT with PDLIL Interrogation of DUT with PDLIL Interrogation of DUT with PDL
PDL in the DUT can make erroneous values in measuring IL and etc.
1 2 3 4 5
0
2
4
6
8
10
PS OFF
PDL AVG
Inse
rtio
n L
oss
(d
B)
Samples
PS ON
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Polarization Induced Phase noisePolarization Induced Phase noisePolarization Induced Phase noise
Polarization induced noise
Interferometer output
Noise floor whenscrambler Off30dB
Noise floor whenscrambler ON
A. D. Kersey, et. Al., JLT, Vol. 8, No. 6, 838 (1990)
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other applications...other applications...
• Pump Polarization Dependent Gain in EDFA
1480 nm, 980nm version is availableother wavelengths are also available.
• Polarization modulator applicationssensors, lasers, and etc.
• Polarization Dependent Loss measurement
PDL Multimeter under development
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ConclusionsConclusionsConclusionsConclusionsConclusionsConclusionsConclusionsConclusionsConclusionsConclusionsConclusionsConclusions
•• Solves PDG/PHBSolves PDG/PHB in long-haul systems.in long-haul systems.
•• Component characterizationComponent characterization without polari without polarization dependence.zation dependence.
•• ManufacturingManufacturing filters or WDM component. filters or WDM component.
•• Removes Polarization induced phase noiRemoves Polarization induced phase noisese or errorsor errors in Fiber Interferometersin Fiber Interferometers
•• Polarization SimulationPolarization Simulation..
All Fiber Polarization ScramblerAll Fiber Polarization Scrambler
Future worksFuture works Fast PDL measurementFast PDL measurement